//--------------------------随机字符-------------------------- 
//str_0 长度 
//str_1 是否大写字母 
//str_2 是否小写字母 
//str_3 是否数字 
function random_str(str_0, str_1, str_2, str_3) {
	var Seed_array = new Array();
	var seedary;
	var i;

	Seed_array[0] = ""
	Seed_array[1] = "A B C D E F G H I J K L M N O P Q R S T U V W X Y Z";
	Seed_array[2] = "a b c d e f g h i j k l m n o p q r s t u v w x y z";
	Seed_array[3] = "0 1 2 3 4 5 6 7 8 9";

	if(!str_1 && !str_2 && !str_3) {
		str_1 = true;
		str_2 = true;
		str_3 = true;
	}

	if(str_1) {
		Seed_array[0] += Seed_array[1];
	}
	if(str_2) {
		Seed_array[0] += " " + Seed_array[2];
	}
	if(str_3) {
		Seed_array[0] += " " + Seed_array[3];
	}

	Seed_array[0] = Seed_array[0].split(" ");
	seedary = ""
	for(i = 0; i < str_0; i++) {
		seedary += Seed_array[0][Math.round(Math.random() * (Seed_array[0].length - 1))]
	}
	return(seedary);

}